New studies published in the journal JAMA this week present an alarming picture of the shifting demographics of the country's obesity problem. For nearly three decades, American men and women have been mostly growing fatter together. But in recent years, for reasons researchers still don't understand, women have broken away with more of them becoming fatter faster.

According to an analysis of the latest government statistics, a staggering 40 percent of women now meet the criteria for being obese. That means that their body mass index, or BMI, is 30 or higher. So, a 5-foot-9-inch woman would weigh more than 203 pounds. The numbers, published Tuesday, were based on data collected in 2013 and 2014 from a nationally representative sample of 2,638 adult men (with an average age of 47 years) and 2,817 women (with an average age of 48 years).

A second study in the same journal found a small increase in teenagers with obesity during those same years.

In an editorial accompanying the study, JAMA editors Jody W. Zylke and Howard Bauchner wrote that a lot of research and attention have been directed toward treating obesity through drugs and procedures. But, they argue, this won't solve the problem.

"The emphasis has to be on prevention, despite evidence that school- and community-based prevention programs and education campaigns by local governments and professional societies have not been highly successful," they said.

Among the major findings of the study:

1. For men, current smokers were more likely to be obese. This same association was not seen in women.

2. Women with an education beyond high school were significantly less likely to be obese.

3. For all U.S. children ages 2 to 19, the prevalence of obesity in 2011-2014 was 17 percent.

4. Over the past 25 years, there has been a positive shift in the very youngest Americans - perhaps signaling that efforts such as first lady Michelle Obama's campaign to get kids to move more are working - with the obesity prevalence decreasing among those ages 2 to 5 and leveling off in children ages 6 to 10.